Introduction
Java HttpURL connection class is a popular choice among Java developers for connecting with web servers, and the Android development team has formally recommended using it wherever feasible.
Java.net.HttpURLConnection Class in Java
HttpURLConnection is an abstract class that extends the URLConnection class. It inherits all of the functionality of its parent class, plus HTTP-specific capabilities. It is another class that is used for the more secure HTTPS protocol.
You may obtain information from any HTTP URL using the HttpURLConnection class, such as header information, status code, response code, and so on.
HttpURLConnection Class Constructor
It creates an instance of the HttpURLConnection class.
Syntax
protected HttpURLConnection(URL u)
Parameters :
u - the URL, Constructs the httpurlconnection to specified URL.
Java HttpURLConnection Methods
Method |
Syntax |
Description |
| getResponseCode() |
Syntax - protected int getResponseCode() 1xx : Information 2xx : Success 3xx : Redirection 4xx : Client error 5xx : Server error |
Used to obtain the server's response status. |
| setRequestMethod() |
Syntax- protected void setRequestMethod(String method) throws ProtocolException Parameters- method- Must be any one of the following- GET, POST, HEAD, OPTIONS, PUT, DELETE, TRACE Throws- ProtocolException - If the method is not valid for http. |
This function is used to specify the request method. The default is GET. |
| getRequestMethod() | Syntax - protected String getRequestMethod() | Returns the request method. |
| getResponseMessage() |
Syntax - public String getResponseMessage() 200 - OK 404 - NOT FOUND |
Retrieves the response message. |
| getHeaderField() |
Syntax - public String getHeaderField(int n) Parameters- n - Index of the header field. |
The nth header field is returned, or null if it does not exist. It overrides the URLConnection class's getHeaderField function. |
| setFixedLengthStreamingMode() |
Syntax - public void setFixedLengthStreamingMode(long n/int n) throws IllegalStateException Parameters- n - Length of content to be written. Throws- IllegalStateException: If the specified length of content is not written on the outputstream. |
If the length of the material to be written on the outputstream is known ahead of time, this method is used to set it. |
| setFollowRedirects() |
Syntax - public void setFollowRedirects(boolean b) Parameters- b : Must be true or false. |
Sets whether or not 3xx response code queries are automatically routed. |
| getFollowRedirects() | Syntax - public static boolean getFollowRedirects() | Returns true or false depending on whether or not automatic redirection is enabled. |
| disconnect() | Syntax- public void disconnect() | Indicated that further queries to the server are highly unlikely. |
| usingProxy() | Syntax - public boolean usingProxy() | Returns true if the connection was formed using a proxy, otherwise false. |
| setChunkedStreamingMode() |
Syntax - public void setChunkedStreamingMode(int n) throws IllegalStateException Parameters- n - length written in each chunk. Throws- IllegalStateException- If some different streaming mode is enabled. |
When the length of the content is unknown, this mode is used. Instead of producing a fixed-length buffer and writing it to the server, content is divided into chunks and then written. All servers do not support this mode. |
| getPermission() | Syntax - public Permission getPermission() | Gets the permissions needed to connect to the target host and port. |
| getErrorStream() |
Syntax - public InputStream getErrorStream()
|
If the server cannot be reached or an error has occurred, this method returns the error stream. It may offer instructions on how to resolve the server problem. |
| setInstanceFollowRedirects() |
Syntax - public void setFollowRedirects(boolean b) Parameters- b : Must be true or false. |
Sets whether this instance of httpURLconnection will automatically redirect 3xx response code requests. It overrides the setFollowRedirects argument, which is more general. If setFollowRedirects is not given, the instance will redirect using setFollowRedirects (). |
| getInstanceFollowRedirects() | Syntax - public boolean getFollowRedirects() | Returns true or false depending on whether automatic instance redirection is enabled or disabled. |
Also see, Duck Number in Java and Hashcode Method in Java
How to get the object of HttpURLConnection class
The URL class's openConnection() method returns an object of the URLConnection class.
Syntax:
public URLConnection openConnection()throws IOException{}
As seen below, you may typecast it to HttpURLConnection.
URL url=new URL("https://en.wikipedia.org/wiki/Java_(programming_language)");
HttpURLConnection huc=(HttpURLConnection)url.openConnection(); Java HttpURLConnection Example
import java.io.*;
import java.net.*;
public class HttpURLConnectionDemo{
public static void main(String[] args){
try{
URL url=new URL("https://en.wikipedia.org/wiki/Java_(programming_language)");
HttpURLConnection huc=(HttpURLConnection)url.openConnection();
for(int i=1;i<=8;i++){
System.out.println(huc.getHeaderFieldKey(i)+" = "+huc.getHeaderField(i));
}
huc.disconnect();
}catch(Exception e){System.out.println(e);}
}
} Output
Date = Thu, 17 Feb 2022 03:46:11 GMTVary = Accept-Encoding,Cookie,Authorization
Server = ATS/8.0.8
X-Content-Type-Options = nosniff
P3p = CP="See https://en.wikipedia.org/wiki/Special:CentralAutoLogin/P3P for more info."
Content-Language = en
Last-Modified = Wed, 16 Feb 2022 04:03:18 GMT
Content-Type = text/html; charset=UTF-8
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